Malignant thymoma with extrathoracic metastasis: a case report and review of literature.

A case of invasive thymoma with metastasis to liver and brain is presented. The incidence, sites of involvement, and the different histological types of metastatic lesions are discussed. Review of the literature shows that the important prognostic factors are the infiltrative nature, the extent of the tumor at the primary site, and associated syndromes like myasthenia gravis and red cell hypoplasia. Patients with noninvasive thymoma have excellent survival by surgery, compared to a reported low (23%) five-year survival with invasive type. The average time of survival after the appearance of metastasis is about one and one-half years.